Bituminous pavement.



UNITED STATES PATENT OFFICE.

. FREDERICK J WARREN, OF NEWTON, MASSACHUSETTS; RALPH L. WARREN, OFBROOKLIN E, AND FRANK G. CUTTER, OF BOSTON, MASSACHUSETTS, ADMINISTRATORS OF SAID FREDERICK J.

WARREN, DECEASED.

Specification of Letters Patent.

Patented Sept. 12, 1905.

Application filed April 6, 1903- Serial No. 151,416.

To aZZ whom it may concern:

Be it known that I, FREDERICK J. WARREN, a citizen of the United States,and a resident of Newton, in the county of Middlesex and State ofMassachusetts, have invented a new and useful Improvement in BituminousPavements, of whichthe following is a full, clear, and exactdescription.

Heretofore it has been customary in the manufacture of paving materialto conduct at the works or before mixing with the mineral ingredientsall the processes involved in making the cement and then to reheat andmix the completed cement withthe stone preparatory to laying thepavement. This reheating has been necessary for the reason that thecement as stored and transported is in a comparatively hard and solidform and in this form could be supplied to the mixer only in chunks.These chunks could not be intimately mixed with the minerals, nor couldthey be melted and united with such minerals at temperatures to whichthe minerals are ordinarily heated for practical purposes and bestresults. To reduce the cold chunks of cement to a liquid form, requiresheat considerably in excess of that required to combine the liquidcement with the minerals, and such reducing heat is ordinarily suppliedin the cement-reheater. In the original preparation of the cement at theworks it has been customary wherever the natural bitumens have been toohard or brittle to flux them with heavy oils until of the properconsistency, or if the natural bitumens have been too soft or oily ithas been usual to remove the excess of oil. In my copending application,Serial No. 42,627, and my patents Nos. 727,506 and 727,507 I havedescribed other processes involving the production of more perfectcements than theretofore known. In accordance with the common procedureand understanding of those engaged in the art all these processes are,as stated, conducted at the works or before mixing with the mineralingredients. There are, however, several objections to this procedure offirst making the cement and then at some future time applying it to themineral ingredients of the intended roadway. The finished cement cannotbe as readily and economically handled as desirable. Again, in meltingthe cement at the place of mixing with the mineral ingredients much heatand consequently much fuel and considerable apparatussuch as kettles,&c.are necessary, and it is diflicult to heat the cement and retain itheated at a proper and uniform temperature for. such ments and to theutilization in place thereof of such heat and energy as may be suppliedto the interior of the stone-mixer.

My invention further relates to the separate preparation at the works orelsewhere of elements to compose, when united, the completed bituminouscement and to the mixing and uniting of such elements preferablysimultaneously with each other and with'the stone in the mixer by meansof the heat of the stone and the agitation imparted through the same inthe mixer. The said elements produced by me as part of this inventionconsist usually of a fluid preferably adapted to be handled cold and ofa comparatively dry resinous bitumen. I also use when desired suchelements as pulverized stone, pulverized clay, sand, soapstone, or otherpowder, such as carbon for modifying the character of the cement, as setforth, for instance, in my Patent No. 727,507.

As has already been indicated, there are va-' rious known methods,several of which have been invented by me, for producing cements fromdifferent bitumens and rendering themsuitable for various purposes. makethe cement fromnatural hard asphalts, in themselves hard enough topulverize and in this case to form the base of the resinous element. Iuse either the crude material as found in nature or any hard bituminoussub- There is always a tendency to over- Preferably I stance which initself is resinous and dry enough to permit its powdering. This resinouselement I produce in any of theone orcarbon for fluxing thebase, andthis hydro-- carbon may be any one of those fluid or semifluidbituinens, either containing some or no resinous matter, and the natureof the fluid material may vary anywhere from an oil without resinousmatter to an oil combined with resinous bituminous matter, either in afluid or semifluid state. I may find it advisable in some cases to havethe softer constituents of the bitumen of such a firmness that a certainamount of heat would be necessary to make such constituents fluid,whereas I may use oily substances of any class. The best one possible tobe used is such a heavy oil as has an asphalt base or has been removedfrom an asphalt, as covered by my Patent No. 727,506. I may. however,first make the cement at the works of a standard grade in any methodknown to the art of making a standard bituminous cement, either fromcoal-tar, asphalt, or other natural or artificial bituminous substances,and then separate the cement into two parts, preferably taking away justenough of the oil constituents to permit the resinous matter topulverize and form a powder which will not reunite in transportation. Itis not necessary, however, to stop the separation at this particularpoint, but when stopped at such a point there is less danger of changingthe nature of the material by creating a molecular disruption, and thefiuid material would under these circumstances be more fluid than if theseparation were carried on to a point where the resinous matter is morebrittle. In some cases, however, the creating of the molecular changewhich would occur in the cement I deem advisable, and in such case I'might find it necessary to carry the separation on further so as to efiect the molecular change which in itself might improve the physicalproperties of the cement when recombined.

Having obtained the fluid and solid cement elements or constituents inany of the ways above set forth, I store them separately and retain themseparately until the time for cementing the minerals. The stone or othermineral elements are then heated, the cement elements introduced intothe mixer, and the cement thus made and applied to the stone by a singleact. In mixing the bituminous and other substances as indicated they aresubdivided into very minute sections and in such subsections the workingof the stony elements against each other and with the bituminoussubstances in the mixer brings about a practical agitation whichcombines the materials under the most advantageous circumstances, usedat relatively lower temperatures than would be possible under any othermethod yet introduced. Depending upon the nature of the hard bituminousand other substances and the fluid bituminous substances and dependingalso upon the temperature, the subdivided substances will combine almostinstantaneously. The harder or more resinous the bituminous substancesthe higher the temperature required in the mineral matter. The morefluid the liquid hydrocarbons the more readily does the combination takeplace at low temperatures-that is to say, the temperature at which thecombination takes place satisfactorily depends entirely upon thephysical and chemical properties of the subdivided substances. I heatthe stony ingredients sufficiently to bring the consistency of the fluidbitumen to the proper point for the Working of the mixture. The higherthe temperature the more readily will the substances unite.

In my invention as above set forth the supplying of the elements in theform described permits of such a ready intermingling and intimateassociation of the same with the minerals that the comparatively lowtern peratures of the elements sufiice to bring about the union, andthus the greater heat of the reheater is not required to be attained inthe mixer. This is an important feature and clearly involvesconsiderably more than the mere discarding of the reheater itself.

It is obvious that slight changes and modifications could be made in theselection and production of my cement and its elements and in themethods of applying the same to the minerals as herein set forth withoutinvolving a departure from the spirit of the invention.

By stony ingredients I mean any earthy or mineral matter of any sizethat may be combined with the elements forming the cement at the timesuch elements are associated, and in lieu of heating one of the elementsor the mineral or earthy ingredients I may employ a temporary liquefierand fixer which preferably is combined with the elements of the cementand the earthy or mineral ingredients at the time they are allassociated together, and this may be done at atmospheric temperatures.

Having thus fully described my invention, I claim and desire to secureby Letters Patent of the United States- 1. A method of making a sheetpaving material consisting in making the bituminous cement thereof andsaid material simultaneously by agitating while heated, minerals andelements adapted when combined to form a cement of the constituency andconsistency of sheet paving-cement.

2. A method of making a sheet paving material consisting in making thebituminous cement thereof and said material simultaneously by agitatingwith heated minerals, fluid and solid elements adapted when combined toform said cement, the heat of said minerals acting to effectuate thecombination.

3. A method of making a sheet paving material consisting first in thepreparation of a fluid element and such solid elements as will whencombined form a bituminous cement andthen simultaneously making saidpaving material and the cement thereof by mixing IIO and agitating Whileheated, minerals and said fluid and solid elements.

4. A method of making a sheet paving m'aterial consistingin firstdividing a bitumen into a fluid element and such solid elements as willwhen combined form a bituminous cement and then simultaneously makingsaid paving material and the cement thereof by mixing and agitating saidfluid and solid elements with mineral ingredients at a heat sufficientto combine the whole.

5. A method of preparing and laying a sheet

